Antibiotic-impregnated gauze pads and method of making same



Patented June 8, 1954 UNITED STATES PATENT OFFICEANTIBIOTIC-IBIPREGNATED GAUZE PADS AND METHOD OF MAKING SAME 3 NoDrawing. Application August 24, 1950,

Serial No. 181,328

4 Claims. 1 My invention relates to an improvement in the prophylacticproperties of gauze pads which are utilized for the protection of bothminor and major wounds.

It is well known that the function of gauze pads from contamination withoutside dirt and debris,

the common gauze pad offers no protection against the development andmultiplication of bacteria in and around the wound surfaces. Practicallyall wounds, be they major or minor, are contaminated with bacteria atthe time they occur. 'I -many of these wounds there are sufficient boddefenses to protect the patient from invasion by these contaminatingbacteria. As a matter of fact, many minor wounds rarely become franklyinfected because of the hosts natural resistance to the contaminatingbacteria. The relatively few bacteria contaminating wounds are usuallyphagocytised by the leukocytes (engulfed and destroyed). These whiteblood cells are one of the agents of the bodys resistance. However,there are a number of wounds which become so heavily infected at thetime they are obtained that the large number of bacteria presentovercome the resistance of the individual and serious and sometimesfatal infections ensue. This is particularly true in the war wounded-where large wounds are incurred under most difficult conditions. Suchwound become badly contaminated with mud, dirt, and debris which arecarried into the wound by the impact of shrapnel, bullets, or metallicfragments and, because of the distances back to base hospitals, the

bacteria have time to develop and multiply. Even in minor wounds,bacteria will multiply if the hosts resistance is not sufiicient toovercome the bacterial invasion.

It is well known that the various antibiotics are both bacteriostaticand bactericidal; that is, they not only inhibit the growth of somebacteria but certain antibiotics actually kill bacteria on contact. Forexample, penicillin is considered to be a bactericidal agent (killsbacteria) while the newer antibiotics such as aureomycin,chloramphenicol, and terramycin are considered mainly to bebacteriostatic (inhibit growth of bacteria) In addition to the fact thatsome antibiotics are bacteriostatic and others bactericidal, it is wellknown that all antibiotics are selective in their action againstmicroorganisms. For example, penicillin is active against the so-calledGram-positive bacteria such as streptococci and staphylococci while anantibiotic such as streptomycin is more active against the so-calledGramnegative bacteria such as those of the colonaerogenes group oforganisms. Furthermore, antibiotics such as aureomycin have activityagainst some Gram-positive and some Gramnegative bacteria but are activeagainst certain of the large viruses and rickettsia. It is well known bythose in the antibiotic field that no one antibiotic is capable ofantagonistic action against all Gram-positive and Gram-negativebacteria, A proper combination of two or more antibiotics would be mostvaluable in the prophylaxis of wounds if the patient could be protectedagainst the large variety of bacteria likely to infect such wounds.

It is an object of my invention, therefore, to produce a gauze padimpregnated with antibiotics that will be efiective against all orpractically all bacteria which may be expected to infect and develop ina wound.

It is known that most antibiotics are not stable in solution and thatthey must be dried to a very low moisture content if they are to retaintheir efiectiveness. It is therefore another object of my invention toimpregnate gauze bandages with antibiotics so that the antibiotics willremain stable and eiiective when put to practice. Other objects and usesof my invention will become apparent from the following description.

I am aware that both streptomycin and bacitracin have been usedseparately to treat wounds and to prevent infection of wounds. Theseantibiotics are prepared usually in an ointment base for this purpose. Iam not aware that polymyxin has been used for this purpose although forthe treatment of certain wounds and for prophylactic purposes there isno sound reason why this antibiotic should not be used in an ointmentbase to act against certain specific types of bacteria.

I believe, however, that the use of the three antibiotics streptomycin,bacitracin and polymyxin, in combination in the manner in which I amabout to disclose, is distinctly new. These three antibiotics I chooseto utilize for impregnation of gauze pads because of their wideantibacterial spectrum and because of the synergistic action obtainedwhen these three antibiotics act together. By synergism I mean that thecombined effect of the three drugs is greater than the sum of theeffects of the individual drugs. A combination of these threeantibiotics in the proper proportions, properly impregnated in the padto prevent deterioration of them, I have discovered will act againstboth Gram-positive and Gram-negative bacteria. It is not my intentionthat these impregnated gauze pads be utilized alone for the treatment ofinfected wound but rather as a prophylactic preparation to prevent thedevelopment and spread of bacteria which normally contaminate mostwounds. There are other and more effective means of treatment for suchwounds and it is my opinion that the antibiotic-impregnated gauze padswould not be sufficient in themselves for such treatment once spread ofinfection had occurred. These pads could be used, however, as asupplement to other forms of treatment such as parenteral and oraltherapy with antibiotics or other chemotherapeutic agents.

In accordance with this invention, I have discovered that by combiningstreptomycin, polymyxin, and bacitracin in solution and impregnatingthem in gauze pads, a preparation is obtained which approaches the idealfor prophylactic treatment of wounds. This preparation has an importantadvantage over the use of a single antibiotic for this purpose in thatit provides antibacterial activity against both the Grampositive andGram-negative bacteria but in addition a synergistic efiect is obtained.It is made readily available at the site of infection and in sufficentconcentrations to inhibit growth or destroy the bacteria present in thewound. During and following operations even under the best of asepticconditions in a hospital, minor contaminations occur from air bournebacteria, such pads used as sponges and as a covering for the operativewound are of great value in protecting the patient against bacterialinvasion.

The antibiotics terramycin, aureomycin and chloramphenicol, are activeto a degree against some Gram-positive and Gram-negative bacteria.Because of their selectivity and similarity of action however, theywould not be emcient when used alone or together in controlling allorganisms that might possibly infect wounds. Any one of theseantibiotics, terramycin, aureomycin, and

chloramphenicol, which act very similarly against bacteria could be usedin place of streptomycin. Thus a combination of aureomycin, bacitracin,and polymyxin; terrarnycin, bacitracin, and polymyxin; orchloramphenicol, bacitracin and polymyxin could be utilized similarly toimpregnate gauze pads in the same manner that acombination ofstreptomycin, bacitracin, and polymyxin is used.

I choose to use a combination of streptomycin, bacitracin, and polymyxinfor the following reasons. All three of the drugs, aureomycin,terramycin, and chloramphenicol, not only act similarly on Gram-positiveand Gram-negative bacteria but in addition it is known that organismsthat become resistant to one of these drugs are resistant to the othertwo as well. This is not true in the case of the combinationstreptomycin-bacitracin-polymyxin, since organisms resistant tostreptomycin are not resistant to other antibiotics. I choose to usebacitracin in place of penicillin, both of which are active againstsimilar organisms, because bacitracin does not cause allergic(sensitivity) anifestations when used locally in wounds as doespenicillin. Another advantage in the streptomycin-bacitracmpolymyxincombination is that the latter drug, namely polymyxin, is active againstorganisms in the Ps udomonas acruginosa group and this is not true tothe same degree for any of the other antibiotic drugs mentioned.Organisms in the Pseudomonas aeruginosa group are those that causedevelopment of so-called green pus and these organisms are commonlyfound in infected wounds.

Although the antibiotics streptomycin, bacitracin, and polymyxin may beincorporated in gauze bandages of a variety of sizes, for demonstrationand simplicity I choose to use gauze pads approximately 3 inches by 3inches containing approximately of a yard of material. Furthermore,although a number of concentrations of antibiotics per square inch ofpad are successful in the prophylactic treatment of wounds, I have foundthat 1,000 micrograms of streptomycin per square inch, 1,000 microgramsof polymyxin per square inch (the polymyxin utilized is 50% to ofpurity), and 50 units of bacitracin per square inch are adequate. In thepreparation of antibiotic-impregnated gauze pads, it is essential thatat least a 10% overage be utilized to account for losses which occurduring manufacture.

All the antibiotics presently in use, and these include the major ones,penicillin, streptomycin, dihydrostreptomycin, aureomycin,chloramphenicol, terramycin, bacitracin, and polymyxin, are not stableto any great degree in solution. Thus in the process of impregnation ofthe gauze pads with antibiotics, it is essential that precautions betaken to prevent deterioration of the antibiotics during the processing.If the antibiotics in solution are heated above room temperature (25 C.)during the process of manufacture, the antibiotics are even moreunstable; and when sufiicient heat is applied the antibiotics may becompletely destroyed. In this process of degradation or break down ofantibiotics, two factors are involved-temperature and time. For example,when penicillin is placed in aqueous solution and refrigerated, it willmaintain its potency for at least 48 to '72 hours without significantloss of activity. However, the same penicillin solutions will lose theirpotency in a matter of a few hours if held at incubator temperature (37C.). Thus it becomes important in the impregnation of gauze withantibiotics that the time and temperature elements be carefullycontrolled. If the antibiotics are placed in aqueous solutions and thenimpregnated into gauze pads, the time of drying to eliminate the watermay be inordinately long so that destruction or partial loss of potencyof the antibiotics results. This loss of potency just described can beovercome to a considerable extent if the gauze pads containing the watersolutions of antibiotics are frozen and then dried under vacuum.-Iowever, this is a time consuming and expensive operation.

I have discovered that the time element which aifects stability, and thetemperature element which similarly aifects stability can be obviatedfor all practical purposes by the use of a highly volatile solvent suchas methanol (absolute methyl alcohol). This solvent is capable ofdissolving readily all three antibiotics, namely streptomycin (thetrihydrochloride calcium chloride double salt), bacitracin, andpolymyxin. Although streptomycin sulfate is also available commercially,I choose to use streptomycin trihydrochloride calcium chloride doublesalt because the latter salt is considerably more soluble in methanolthan the sulfate salt. Methanol is extremely volatile and therefore itmay be removed quickly from the gauze pads by evaporation. Evaporationis hastened by the application of a blast of warm air.

In the preparation of antibiotic-impregnated gauze pads, it is essential(to avoid contamination of the pad with bacteria) that aseptic techniquebe used throughout the process. Thus the gauze pads utilized are heatsterilized prior to impregnation and all processing thereafter iscarefully controlled to avoid contamination with bacteria. Thesterilization may be done by steam sterilization at 120 C. for minutesor by the application of dry heat at a temperature of 110 C. for from 8to 12 hours.

The impregnation of the sterile gauze pads may be accomplished in thefollowing manner.

(1) Prepare stock solutions as follows in absolute methyl alcohol(methanol).

Streptomycin trihydrochloride c a l o i u m (2) Prepare the workingsolution by mixing equal parts of the above stock solutions. Thus, theworking solution will contain 2,000 meg/ml. of streptomycin, 10cunits/ml. of bacitracin, and 2,000 meg/ml. of polymyxin B.-

The standard sterile 3 inch by 3 inch folded gauze pad containingapproximately of a square yard of gauze is dipped into the workingsolution and, after it is thoroughly saturated, removed and the excesssolution extruded by applying pressure. The pressure applied should besuch that approximately 5 ml. of the working solution remains in thepad. The pressure necessary to extrude the excess methyl alcoholsolution can be predetermined by weighing a pad before immersion in thesolution, weighing it after immersion, and then trial squeezing the padto remove the excess solution to allow approximately 5 ml. to remain inthe pad. The pad is dried in a blast of warm air until all methylalcohol has been evaporated and the pad is dry (this takes approximatelyone to two minutes). All operations are performed under asepticconditions.

A second method of preparing gauze pads impregnated with antibiotics isas follows:

Rolls or bolts of sterile gauze are placed on a roller and one endallowed to dip into the working solution described above. The end of thegauze is allowed to pass under a second roller which is fixed in the pancontaining the solution so that the gauze, as it passes under theroller, is made to pass through the solution. As the end of the gauze ispulled forward through the solution and passes the pan containing thesolution, a blast of warm air drives out the excess methyl alcoholpresent, thus drying the gauze. The dry gauze is attached to a thirdroller and may be rewound either by hand or by power. All operationsincluding the folding of the gauze to form the pads are carried outunder aseptic conditions.

With the stock solution described above, the impregnated gauze pads(folded) contain per square inch approximately 1,000 mcg. ofstreptomycin, 1,000 mcg. of polymyxin, and units of bacitracin.

After preparation, the gauze pads described are placed in sterileenvelopes. For assay purposes, 1. e., to determine the amount of eachantibiotic impregnated into the pads, several square inch portions ofthe pads are cut and extracted with water and the water assayed for itsantibiotic con-- tent. The assay methods utilized for streptomycin,bacitracin, and .polymyxin are those described in sections141.101,.141xi01, and 141.39 of section 507 of the Food, Drug, andCosmetic Act of 1938. On several occasions twelve individual square inchportions of antibiotics-impregnated gauze pads prepared as describedabove have been assayed. It was found that to of the three antibioticsimpregnated into thepads can be recovered by the assay proceduresdescribed above. These assay results are well within the experimentalerror of these methods.

To demonstrate the antibacterial activity of the gauze pads, squarecentimeter portions are cut and placed aseptically on Petri dishescontaining agar previously inoculated with bacteria (a) Microccccusflames, and (b) Bacillus bronchiscpticus. The Petri dishes are thenplaced in an incubator at 37 C. ifor a period of 24 hours. At the end ofthistime immediately surrounding the square portions of theantibioticdmpregnated gauze pads'and extending outward from the pad forone to two centimeters or more is found a clear zone of inhibition ofgrowth of the bacteria With which the agar in the Petri dishes wasinoculated. The antibiotics present in the pads are extracted from thepads by the moisture present in the agar used as a medium for growth ofthe bacteria thus simulating the absorption of the antibiotics from thepads by the moisture or serous exudates of wounds. The antibiotics sowithdrawn from the pads diffuse through the agar thus preventing thegrowth of, or xilling the bacteria in the clear zone. Beyond the clearzone the bacteria grow profusely. The numbers of bacteria acted upon bythese antibiotics in this demonstration exceed by several million timesthe numbers normally present in wounds thus demonstrating inhibition ofthe bacteria which represent both the Gram-positive (M icrococcus flaws)and the Gram-negative (Bacillus bronchisepticus) groups of organisms.

Having thus described my antibiotic-impregnated gauze pad, its method ofuse, and its activity against both Gram-positive and Gramnegativebacteria, 1 am aware that the exact portions of the three antibioticsmay be varied and should be varied to suit different types of wounds anddifferent size pads but that such variation is well within the preceptsof the invention and such as may be understood to those experienced insuch matters and that it does not depart from the spirit of my inventionnor the scope of the impending claims.

I claim:

1. The method of impregnating a gauze pad with a stable therapeutic,antibiotic composition having synergistic bactericidal action and a wideantibacterial spectrum which comprises issolving bacitracin, polymyxinand streptomycin trihydrochloride calcium chloride double salt inmethanol, impregnating said pad with the resultant solution, andremoving the methanol from said pad by evaporation, each of saidantibiotic compounds being present in the dried impregnated gauze pad ina minimal amount which, if used alone, would produce a bacteriostaticeffeet.

2. The method of impregnating a gauze pad with a stable therapeutic,antibiotic composition having synergistic bactericidal action and a wideantibacterial spectrum which comprises dissolving bacitracin, polymyxinand streptomycin trihydrochloride calcium chloride double salt inmethanol, saturating said pad. with the resultant solution, removing theexcess solution from said impregnated pad and evaporating saidimpregnated pad to dryness for a period of time ranging from one to twominutes, each of said antibiotic compounds being present in the driedimpregnated gauze pad in a minimal amount which, if used alone, wouldproduce a bacteriostatic effect.

3. A gauze pad for the prophylactic treatment of wounds, said pad beingimpregnated with a therapeutic, antibiotic composition havingsynergistic bactericidal action and a wide antibacterial spectrum, saidcomposition comprising bacitracin, polymyxin and streptomycintrihydrochloride calcium chloride double salt, each of said antibioticcompounds being present in a minimal amount which, if used alone, wouldproduce a bacteriostatic effect.

4. The gauze pad set forth in claim 3 wherein said pad is impregnatedper square inch with about 50 units bacitracin, about 1000 micrograms ofpolymyxin having a purity of 50 to '70 per cent and about 1000micrograms of streptomycin trihydrochloride calcium chloride doublesalt.

8 References Gited in the file of this patent UNITED STATES PATENTSNumber Name Date 2,531,869 Alburn Nov. 28, 1950 2,594,374 Welch Apr. 29,1952 FOREIGN PATENTS Number Country Date 581,234 Great Britain Oct. 4,1946 OTHER REFERENCES

1. THE METHOD OF IMPREGNATING A GAUZE PAD WITH A STABLE THERAPEUTIC,ANTIBIOTIC COMPOSITION HAVING SYNERGISTIC BACTERICIDAL ACTION AND A WIDEANTIBACTERIAL SPECTRUM WHICH COMPRISES DISSOLVING BACITRACIN, POLYMYXINAND STREPTOMYCIN TRIHYDROCHLORIDE CALCIUM CHLORIDE DOUBLE SALT INMETHANOL, IMPREGNATING SAID PAD WITH THE RESULTANT SOLUTION, ANDREMOVING THE METHANOL FROM SAID PAD BY EVAPORATION, EACH OF SAIDANTIBIOTIC COMPOUNDS BEING PRESENT IN THE DRIED IMPREGNATED GAUZE PAD INA MINIMAL AMOUNT WHICH, IF USED ALONE, WOULD PRODUCE A BACTERIOSTATICEFFECT.